Anglers frequently use a rod to cast a lure or bait attached to a line in order to place the lure or bait at a desired location in the water where the angler hopes to find fish. Typically, one or more sinkers are attached to the line. The sinker serves to provide sufficient weight on the line to flex the rod during the casting action, and provides weight to carry the line against the resistance of air to the desired location. The sinker then serves to maintain the lure or bait in close proximity to the bottom of a body of water.
Unfortunately, sinkers are prone to snagging on weeds, rocks, submerged branches, and similar obstacles. Snagging typically occurs when the fishing line to which the sinker is connected is moved through the water, either when the line is jerked to jump the lure or bait through the water or when reeling in the line after casting. Such snagging may result in breakage of the fishing line and loss of the sinker, and possibly loss of the lure or bait attached to the line. Breakage of the line due to snagging also requires the user to attach a new sinker and possibly a new lure or bait, taking time away from actively fishing.
The problem of loss of expensive lures can be overcome by employing a bait locating device such as taught in U.S. Pat. No. 5,555,668. The '668 bait locating device floats the lure off the bottom with a flotation member, which is connected to a sinker by a separate sinker line. In the event that the sinker does become snagged, the line to the sinker can be broken, allowing recovery of the fishing line and any expensive lure attached thereto. However, the problem of replacing the sinker still remains.
Traditionally, sinkers have been provided in streamlined shapes in an attempt to resist snagging of the sinker; however, such sinkers can still become lodged between rocks or other obstructions. Additionally, the streamlined shape of such sinkers may prevent them from gripping the bottom surface of a body of water to maintain a lure or bait in a desired position when there is a strong current in the water.
Another concern is the frequent need to change the weight of the sinker to suit conditions such as current, lure or bait size, etc. This has classically been done by replacing the sinker on the line with one of a different weight, or by removing or adding one or more sinkers that are crimped onto the fishing line. Simply replacing sinkers may be time consuming, and requires a substantial inventory of different sinker weights to be carried. Crimped-on sinkers may cause undue wear on the line, and the use of multiple sinkers on the line may increase the risk of one or more sinkers becoming snagged.
In an attempt to make weight changes more convenient, sinker devices have been designed that allow the user to readily change the weight, either by adding or removing weight units to a retaining structure or by removing a weight unit and replacing it with one having a different weight.
A rudimentary example of the first approach is taught in U.S. Pat. No. 3,943,654, which teaches a circular strip which attaches to a line and receives a desired number of discarded spark plugs, which serve as weights. The resulting device has numerous protruding elements and thus appears to be highly prone to snagging on obstructions. Furthermore, the resulting sinker would appear to have a large air resistance, which would limit the distance that it can be cast; this problem is exacerbated by the use of spark plugs, which have a relatively low density compared to conventional sinker materials, for the weight units. A more refined device is taught in U.S. Pat. No. 2,863,253, where a weight attaches to the line and additional weights can be threadably attached in series. The resulting sinker is more compact and lacks the protrusions of the '654 sinker, but the threads employed to attach the weights together may be prone to damage or wear by impacts, grit, and/or corrosion. The threaded connections may also make the weights of the '253 sinker expensive to fabricate. U.S. Pat. No. 2,589,715 teaches a trolling sinker having a shaft on which weight units can be slid, these weight units being retained by blocks that are affixed to the shaft by set screws. The use of set screws complicates the process of changing the weight, and may be difficult to accomplish with wet and/or cold hands, as the angler would need to manipulate small objects to loosen and re-tighten the set screws. U.S. Pat. Nos. 1,858,550 and 2,600,002 teach sinkers having streamlined capsules in which a desired number of balls are placed to adjust the weight. Again, the requirement that the user manipulate several small objects to change the weight may make adjustment of the weight difficult in actual angling conditions. Furthermore, the streamlined capsules would appear to provide relatively little ability to grip the bottom surface, limiting their suitability in conditions where a strong current is present.
The second approach to varying the sinker weight, using a single replaceable weight, is taught in U.S. Pat. Nos. 3,648,398 and 5,461,821. These patents teach sinkers that have a weight held in a resilient tube, to which the line is attached. The weight of the sinker can be readily changed by pulling the weight from the tubing and substituting a different weight. However, these devices appear to be limited in the amount of weight that can be employed in the sinker, since a relatively large weight would require the weight to be excessively long. Such a long, rigid weight may be difficult to cast, may be more prone to snagging, and may provide limited ability to grip the bottom surface. Also, an excessively long weight is difficult to store conveniently. Since the weight is intended to be squeezed out of the tube in the event that the weight becomes jammed by obstructions, it appears that it may be difficult to attaining the right degree of friction between the weight and the tubing such that the weight will not fall out of the tubing when casting, but will slip out of the tubing if it becomes jammed.